It is a key problem in ship construction to improve and guarantee the welding quality of crane base system. In this paper,the welding performance of DH36 thick plate is studied experimentally. The new technology of ceramic backing is adopted to avoid the adverse effects caused by root cleaning. The problem of incompletely welding defects and controlling assembly clearance has been solved about high strength thick plates for ships. The results such as stretch,bend,impact and hardness tests for welded joints can meet the requirement. It has a good reference for welding high-strengthen steel for marine thick plate.